Final answer:
The odd one out on the basis of methods of biodiversity conservation is (D) Gene bank.
Step-by-step explanation:
The odd one out on the basis of methods of biodiversity conservation is D. Gene bank.
Zoological parks, botanical gardens, and national parks are all methods of conserving biodiversity. Zoological parks provide habitats for and conserve various animal species. Botanical gardens, on the other hand, focus on conserving diverse plant species. National parks are protected areas set aside to conserve ecosystems and the species that inhabit them.
In contrast, gene banks are repositories of genetic material, such as seeds or DNA samples, but they do not directly conserve habitats or ecosystems.